Pertinent Insights On The Posterior Approach To Hindfoot Arthrodesis

These authors discuss an innovative approach to a complicated pathology in a 44-year-old patient who had an extensive intraosseous talar cyst with joint involvement.

Tibiotalocalcaneal arthrodesis are often salvage procedures that surgeons utilize for complex Charcot reconstruction, severe post-traumatic arthritis and extensive talar avascular necrosis. Fixation constructs for this procedure have evolved from internal compression screws to retrograde intramedullary nails to a combination of compression screws and plates.

We present a case report of a 44-year-old male who was referred to our clinic with an eight-year history of a painful right ankle and hindfoot. He said the pain was unrelenting with ambulation, especially when ascending and descending flights of stairs as a local deliveryman. He denied any specific foot and ankle trauma. The patient took only non-steroidal anti-inflammatories (NSAIDs) for the daily pain. The patient also denied any tobacco or ethanol abuse.

The patient had no significant past medical history of note. Past surgical intervention on the same ankle included a talar cyst filling with a bone graft in 1996. The physical examination demonstrated limited ankle range of motion and tenderness to the anterior joint line. Subtalar joint range of motion was also limited and painful over the sinus tarsi. No gross angular deformity was present at the ankle or subtalar joints.

Radiographs of the right ankle revealed a large cystic, multi-loculated, dense talar body lesion, occupying over 75 percent of the talus from posterior to anterior and over 50 percent from medial to lateral. Magnetic resonance images (MRI) compared to the aforementioned radiographs demonstrated subchondral irregularities at the posterior subtalar joint and ankle joint. We also noted mild expansion of the talus secondary to intraosseous cystic lesions with fluid-fluid levels that had increased from the last examination in 2005.

We discussed the complicated nature of this talar cyst with the patient and the involvement of both the ankle and subtalar joints. The ultimate diagnosis of a benign talar body cyst and avascular necrosis with joint extension has led to destruction of the joint surfaces and concomitant arthritis and pain. We counseled the patient on the need for a tibiotalocalcaneal fusion as well as all risks, benefits and possible perioperative complications associated with the case.

The goal for this active 44-year-old male was ultimately pain relief with a functional limb. Our surgical goals were to retain as much living talus as possible without violating his transverse tarsal joint, maintain limb length and proper hindfoot-to-ankle alignment, and achieve a successful union.

A Guide To Surgical Technique

We utilized a posterior, trans-Achilles approach for adequate exposure of both joints through a single incision. After performing a 12-cm midline skin incision, we utilized a frontal plane Z-lengthening of the Achilles approximately 6 cm in length. Retraction allowed for complete visualization of the deep crural fascia and compartment.

We dissected down in the interval between the flexor hallucis longus muscle belly and peroneal tendons, and limited retraction to the use of deep Weitlaner retractors to prevent any post-surgical wound complications. This provided excellent visualization of the posterior malleolus, posterior talus and superior calcaneus. We proceeded to retract the distal flexor hallucis longus medially and resected the posterolateral process of the talus, which aided in visualization of the subtalar joint.

After performing a posterior capsulotomy of the ankle and subtalar joints, we placed a Hintermann retractor across the tibiotalar interface and performed subsequent joint resection via curettes and osteotomes. We performed the same for the subtalar joint. In this case, we resected the body of the cystic talus until we approached the viable talar neck. We also used femoral head allograft with bone marrow aspirate and beta-tricalcium phosphate graft (Vitoss, Stryker) to supplement limb length and healing.

We then resected the posterior malleolus with a curved osteotome for adequate plate fixation. Using a posterior tibiotalocalcaneal compression plate (Wright Medical Technologies) with locking and non-locking screws allowed for compression and rigid internal fixation. We also placed an internal bone stimulator across the fusion site.

We subsequently proceeded to adequate closure of the overlying flexor hallucis longus muscle belly and reapproximation of the Achilles tendon with non-absorbable sutures. Then we pursued a layered closure in typical fashion with absorbable subcutaneous sutures and non-absorbable mattress sutures. The patient wore a Jones compression posterior splint and was admitted postoperatively for pain control.

The patient remained in a non-weightbearing cast for six weeks and subsequently transitioned into a weightbearing fracture boot for eight weeks. At this point, serial radiographs revealed trabecular bridging in multiple views. He then began formal physical therapy with a lace-up ankle brace and supportive shoegear. No complications occurred during the postoperative period. At the final follow-up, he had a pain-free plantigrade foot with proper foot to leg alignment. Again, serial radiographs revealed appropriate osseous healing without hardware compromise.

Our surgical technique has evolved in cases of tibiotalocalcaneal fusions without bulk allografts since this case. In addition to the posterior locking plate application, our institution has supplemented interfragmentary screw compression across both joints with 6.5-mm screws while avoiding a plantar incision (see Figure 18).

What The Literature Reveals

The case presented above involved a sensate, active male who presented for a second opinion with a complicated talar avascular necrosis defect. The literature is sparse when salvage of a limb with talar avascular necrosis occurs with successful results.

Devries and colleagues retrospectively reviewed 14 patients included in the RAIN (Retrograde Intramedullary Nail Arthrodesis) database.1 The average age was 47 years old and the most common (36 percent) etiology was status-post talar fracture. Twelve of 14 patients went on to a solid union and eight patients were able to return to preoperative shoegear. The complication rate was 28.6 percent. This relatively large cohort of talar avascular necrosis cases utilizes intramedullary, load-sharing devices with good success.

Surgeons have used multiple fixation types over the years for tibiotalocalcaneal fusions with success. Various authors have described lateral humeral locking plates, anterior locking plates and posterior blade plates.2-5 The development of locking plate technology has revolutionized fixation constructs in foot and ankle surgery, specifically hindfoot and ankle arthrodesis. Biomechanical studies have evaluated the stiffness and load to failure of screws only versus an anterior locking plate and screw construct showing that, as expected, an anterior plate and cross-screw configuration were more stiff in a cadaveric model.6 We used locking plate technology in this case due to the patient’s bone quality and large defect.

DiDomenico has reported on the successful use of an anterior locking compression plate through a posterior approach with compression screws as well.7 There is no study to date comparing posterior locked plate fixation with or without cross-screws to anterior constructs.

A posterior approach to the ankle and hindfoot, as described by many authors, allows for great visualization and exposure.8 One can divide the Achilles tendon either in the coronal or sagittal plane without significant wound complications through a posterior midline incision.

In a systematic review comparing posterior midline and posterior medial leg incision wound complication rates, authors found 7 percent and 8.3 percent complication rates with the midline incision and posterior medial incision groups respectively.9 They noted that more important than incision placement were the associated non-surgical factors, such as comorbidities and postoperative protocols. Also, the angiosomes from the peroneal vessels laterally and the posterior tibial vessels medially, as described by Taylor, meet centrally and allow for the midline incision to heal without incident.10 This approach is also appropriate in cases in which anterior soft tissues do not allow for dissection (e.g. skin flaps, grafts, wounds) and there is very little talar neck to allow for anterior plate fixation options.

In Conclusion

We have described an uncommon pathology and approach for a significant talar body cyst with salvage of the transverse tarsal joint and a successful, pain-free union.

Here are some keys to success.

• Use minimal skin retraction during dissection to prevent any unforeseen wound complications.
• Wide Hintermann retractors are helpful in joint visualization.
• Appropriately visualize the medial neurovascular bundle and peroneal vessels.
• Resection of the large posterior malleolus allows for plate adaptation.
• Posterior plate fixation may be extraperiosteal on the posterior tibia.
• Use two compression screws with one from the posterior tibia to the talar neck and one from the posterior calcaneus to the talar body.
• It is advantageous in a non-neuropathic, sensate patient to avoid plantar neurovascular injury and scar formation.

Dr. McAlister is a Fellow of the Orthopedic Foot and Ankle Center in Westerville, Ohio.

Dr. Hyer is a Fellow of the American College of Foot and Ankle Surgeons, and serves on its Board of Directors. He is the Fellowship Co-Director of the Orthopedic Foot and Ankle Center in Westerville, Ohio.